Sunday, November 25, 2007

"People say to me, 'Are you looking for the ultimate laws of physics?' No, I'm not... If it turns out there is a simple ultimate law which explains everything, so be it — that would be very nice to discover. If it turns out it's like an onion with millions of layers... then that's the way it is." -- Richard Feynman from "The Pleasure of Finding Things Out"

Paul Davies' Op-Ed in the New York Times, "Taking Science on Faith" (November 24, 2007) makes a familiar argument. If he had used the light version of the argument, I might have agreed. But he uses the strong version which is just wrong.

The light argument is: Everyone works with metaphysical assumptions. For example, I have a working assumption that the universe is comprised of matter and energy -- and everything we experience emerges from those two entities. Maybe there is more to the universe than I am guessing. I just haven't seen convincing evidence of anything else yet. So yes, I have a metaphysical assumption and it might be wrong.

Davies argues a much stronger version of this. He states,

"science has its own faith-based belief system. All science proceeds on the assumption that nature is ordered in a rational and intelligible way."

That is demonstrably false.

Quantum physics is not rational or intelligible. On the quantum scale, sometimes "if A then B" -- sometimes "if A then not-B." No one understands why this is the case. But if we perform enough experiments resulting in B or not-B, we can statistically chart the probabilities. That is a rational approach to something we don't understand. The use of probabilities delivers extremely reliable results over the long term. But the actual workings of the quantum world remain mysterious.

Physicists Richard Feynman and John von Neumann are both attributed saying, "You don't understand quantum mechanics, you just get used to it."

The world is not so orderly -- and this is already accepted by scientists. There is a difference between rationality in nature and using rationality to study nature. Davies conflates the two ideas.

Davies continues,

"The laws of gravitation and electromagnetism, the laws that regulate the world within the atom, the laws of motion — all are expressed as tidy mathematical relationships. But where do these laws come from? And why do they have the form that they do?"

Davies presents these as questions that science ignores. Actually, these are vital and pressing questions in the physics community.

The mathematical relationships that he describes as "tidy" are actually pretty hairy. The relationship between gravity and electromagnetism has been a mystery for decades and is the impetus for studies in supersymmetry and the string hypothesis. When relativity and quantum mechanics are combined on the tiniest scales, they generate messy infinities.

The sexiest and busiest theoretical physics happening from Einstein to today has been the attempt to reconcile this problem. But Davies portrays the scientists as in a blithe disregard.

Davies reports,

"Over the years I have often asked my physicist colleagues why the laws of physics are what they are. The answers vary from 'that's not a scientific question' to 'nobody knows.' The favorite reply is, 'There is no reason they are what they are — they just are.'"

First, "nobody knows" is perfectly legitimate answer. It's the kind of answer that gets scientists out of bed in the morning. It's a mystery to solve. "Nobody knows, but maybe we can find out."

Second, we can't assume there is an ultimate explanation. If we found one, that would be nice, just as Feynman said at the top quote. But we can't currently assume such an explanation will be found.

Davies rebukes,

"The idea that the laws exist reasonlessly is deeply anti-rational."

Again, we can't assume that nature has any reasons. But we can still use our rationality to study nature. Nature is what it is. Our rationality helps us discover nature. But we should not assume we will find rationality staring back at us. Currently, we don't.

Davies argues,

"If one traces these reasons all the way down to the bedrock of reality — the laws of physics — only to find that reason then deserts us, it makes a mockery of science."

No, it just means that some phenomena are unintelligible -- as in quantum physics.

A few words about the "laws" of physics. The use of the term "laws" carries some baggage. Plus, it invites additional baggage from those who want to assume a "lawmaker."

Let's take the law of gravity as an example. The law of gravity is one of the most respected ideas in physics. Galileo measured falling bodies at 32 feet/sec/sec. But that measurement turned out to be true only locally. Newton revised this by showing that the strength of gravity is inversely proportional to distance, and in doing so explained planetary motion. Einstein revised Newton, describing gravity in terms of space-time geometry -- which fit better with the orbit of Mercury around the sun. Now Einstein may be under revision as we try to understand the apparently accelerating expansion of the visible universe.

Like our secular laws, physical laws are open to revision. What's more, our current physical laws break down when we go back in time within the Big Bang model.

Our use of the word "laws" is a relic from science's past. Greater minds may be able to think up a better word. But it is important to realize that any scientific explanation is tentative, open to revision, maybe true at one time but not in another time. Modern cosmology now treats "laws" as potentially mutable.

Davies talks about his science education,

"The laws were treated as 'given' — imprinted on the universe like a maker’s mark at the moment of cosmic birth — and fixed forevermore."

It sounds like that education was a disservice. The Big Bang and inflationary models contradict these assumptions.

Leaving the Big Bang aside, let's concentrate on the consistency of scientific findings. Consistency of experimental results is the norm today and makes science possible. The current universe, to our best evidence, is very consistent. That does not necessarily mean that, at its root, the universe is intelligible or has "laws" for a "reason." Consistency and rationality are two different ideas. For example, the quantum world is consistently and dependably irrational.

Davies then touches on the multiverse speculation. This is the idea that our universe is only one of many universes. The other universes may have different physics which may or may not be stable or hospitable to life. He writes,

"In this 'multiverse,' life will arise only in those patches with bio-friendly bylaws, so it is no surprise that we find ourselves in a Goldilocks universe — one that is just right for life. We have selected it by our very existence."

Davies is responding to a line of questioning often called the anthropic principle. "Why is the universe so suited for our existence?" is a way of summarizing the idea. The problem with the anthropic principle is that explores the universe by looking through the wrong end of the telescope.

In the novella Candide, Voltaire ridicules this kind of thinking with the character Dr. Pangloss. Pangloss argues we live in the best of all possible worlds. Evidence for this assertion is that our noses are perfectly designed for resting eyeglasses.

Actually, most of the universe is hostile to human existence. We are not adapted to survive in the vacuum of space (the vast majority of the universe). And if the earth happened to form near the center of our galaxy, the turbulence may have made it impossible for creatures to evolve to the point where they could ask teleological questions.

A better question might be, "Why is our universe productive enough to create life at all?" That might be interesting except that it's likely unanswerable. Our sample set of universes is limited to one. And we don't know what portion of this one is visible to us.

While it's unlikely we are the first life in the universe, we're the only ones we have found. The universe is not teeming with life forms except very locally. A few miles up or a few miles down and you're escaping our humble biota.

If Davies is dissatisfied with speculating on a multiverse, we are in agreement. Unfortunately, he goes further:

"Both religion and science are founded on faith — namely, on belief in the existence of something outside the universe, like an unexplained God or an unexplained set of physical laws, maybe even a huge ensemble of unseen universes, too."

Scientists do not necessarily assume there is something outside the universe. For example, asking what was happening before the universe may be nonsensical because time is part of the universe in question. To paraphrase Stephen Hawking, asking what happened before the beginning of the universe is like asking what land is south of the south pole.

Davies' argument misconstrues the search for "physical laws" as necessarily appealing to something "outside" the universe. Plus, it throws in the problematic multiverse idea for good measure.

Then comes the zinger,

"For that reason, both monotheistic religion and orthodox science fail to provide a complete account of physical existence."

This is a subset of the general rule: "no one can provide a complete account of physical existence."

This is not a controversial point.

The advantage of scientific inquiry is that it admits this ignorance. But Davies tries to use our shared ignorance as a basis for false equivalence.

There is a difference between saying,"The universe seemed to start with a Big Bang, I wonder why?" and"The universe seemed to start with a Big Bang, I wonder who made it?"The second question assumes a particular kind of answer.The first question is more open-ended and parsimonious.

Davies' argument falsely equates the two. It does this by misrepresenting the quest for physical "laws" as a faith-based initiative. Today's cosmology is not so certain.

If Davies was arguing that we are all ignorant of any full explanation of physical reality and we do our best with our assumptions, I would agree. But he goes further to argue that all scientific inquiry is like religion.

In practice, the answer "God made it that way," tends to stop inquiry (and generates an unwarranted amount of certainty these days). On the other hand, all scientific knowledge is tentative.

Even a discovery as well revered as gravity is under continuous scrutiny and revision.